A $90,000 area rug, a pair of guest chairs that cost almost as much, a $35,000 commode and a $1,400 trash can—these are just a few of the expenses from a remodeling of John Thain's office when he took over as Merrill Lynch's chief executive officer in December 2007. The total bill came to an astonishing $1.2 million—about the price of five average single-family homes.

Those same remodeling expenses contributed to Mr. Thain's resignation just over a year later, after Bank of America bought Merrill, and helped to define...